Late January is the coldest point of the year, and it leads into the snowiest. Such harsh weather is a two-edged sword for birders.

The number of birds declines as some move south and others succumb to the cold; what birds remain sulkily conserve their energy in sheltered spots; and the process of looking for birds is a chilly one for all parties concerned.

On the other hand, birds tend to cluster around whatever resources are available — feeders or berry bushes, if they’re songbirds, or in dwindling patches of unfrozen water, if they’re ducks or gulls — making a birder’s search a little easier. And it’s worth recollecting that the migratory movement of birds never quite ceases. On the Vineyard, that means that rarities are always possible.

Case in point: a female summer tanager that turned up Thursday, Jan. 17 at a feeder on private property off Lambert’s Cove Road in West Tisbury. Wolfing down seeds, which are not typical fare for tanagers, and aggressively defending the feeder against all comers, the bird was clearly stressed by whatever travels brought it here. Summer tanagers fall into the “rare but regular” class on the Vineyard; the nearest breeding population is in southern New Jersey, but these colorful birds turn up more or less annually on the Island, most often as “overshoot” migrants in the spring. A winter record like this one is highly unusual in our region, and apparently unprecedented for the Vineyard.

A delayed report of another rarity also deserves mention. A puzzling grosbeak briefly visited a feeder at Katama on Dec. 30. Debby Carter, the alert homeowner, managed to snap a few photos before the bird disappeared, and these circulated among local birders. Streaky and yellowish underneath, the bird is clearly either a rose-breasted grosbeak (regular here in the warm months but very rare in winter) or the western counterpart of that species, a black-headed grosbeak.

Females and immatures of these closely related species can be very hard to distinguish, and Debby’s photos were a little blurry. But I concur with Martha’s Vineyard Times columnist Vern Laux that the bird was a black-headed grosbeak: the breast coloration, limited streaking on the underparts, and distinctive dark upper mandible on the bill all look wrong for rose-breasted. At this season, moreover, the western species may be more likely than the eastern one. Another “rare but regular” vagrant in the East, black-headed grosbeaks have been recorded just nine times previously on the Vineyard, according to the recently published Vineyard Birds II.

The Oak Bluffs waterfront, from Farm Pond around to Eastville, is as productive as it is accessible at this point in the season, and any birder passing this way is well-advised to make a few quick stops. A small group of purple sandpipers has been quite regular on the breakwater across from Waban Park, sometimes joined by a few sanderlings or dunlin, as long as the tide is low enough to expose the rocks. From the bluffs of East Chop, a scattered flock of goldeneyes is generally visible, and I’ve picked out an immature male Barrow’s a couple of times this month among the more usual common goldeneyes.

Long-tailed ducks have also been numerous here. Regionally abundant in winter but historically rather scarce on near-shore Vineyard waters, this elegant duck has grown steadily more common off the north shore in recent years. The Head of the Lagoon is also always worth a stop in winter: a few ring-necked ducks are hanging in there along coots, buffleheads, American widgeons, and a good-sized flock of gulls.

Chipping sparrows — another species growing steadily more common here in the winter — have been among the unruly mob frequenting the feeders at Heidi and Ronnie Schultz’s house in West Tisbury.

The bird hot line 508-627-4922; please be sure to dial one to leave a message in the correct mailbox, or your sighting will be consigned to oblivion among the recorded calls offering credit card consolidation) received several reports of robin flocks this past week. Phyllis Conway reported “hundreds” from her Stonewall Beach home, and Alden Besse, calling the line “for the first time in his 83 years” from Vineyard Haven, also noted a large flock.

While great fun, such flocks are not unusual; robins are highly gregarious in the winter and are often numerous on the Island at this season, feeding mainly on fruits and berries. Winter nocturnal roosts of this species in our region sometimes number in the tens of thousands.

A few red-winged blackbirds also were noted. Nancy Abbot saw one in West Tisbury last Saturday, and a northbound, calling bird passed high over my Oak Bluffs house on the same day. While some red-wings linger into winter on the Island, these recent sightings may reflect very early northbound migrants, prompted into motion by the warm weather last Friday. The Oak Bluffs bird, in particular, appeared to be traveling determinedly. Spring migration, in other words, has begun.